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Serotoninergic receptors in the anteroventral preoptic region modulates the hypoxic ventilatory response
Author(s) -
Bicego Kenia Cardoso,
Gargaglioni Luciane H.,
Nucci Tatiane B.,
Branco Luiz G. S.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb30-c
Subject(s) - methysergide , serotonergic , endocrinology , medicine , antagonist , receptor antagonist , serotonin , 5 ht receptor , receptor , hypothalamus , chemistry , microinjection , hyperventilation , biology
Hypothalamus is a site of integration of the hypoxic and thermal stimuli on breathing and it is known that serotonin (5‐HT) receptors in the anteroventral preoptic region (AVPO) of the hypothalamus mediate hypoxic hypothermia. Once 5‐HT plays a role in the hypoxic ventilatory response (HVR), we investigated the participation of the 5‐HT receptors (5‐HT1, 5‐HT2 and 5‐HT7) into the AVPO in the hypoxia‐induced hyperventilation. To this end, pulmonary ventilation (VE) of male Wistar rats was measured before and after intra‐AVPO microinjection of vehicles, methysergide (5‐HT1/5‐HT2 receptor antagonist, 0.2 and 2 μg/100 nL), WAY 100635 (5‐HT1A receptor antagonist, 0.3 and 3 μg/100 nL) and SB 269970 (5‐HT7 receptor antagonist, 0.4 and 4 μ/100 nL), followed by 1h of 7% O2 exposure. Vehicles or 5‐HT antagonists did not change VE during normoxia. Exposure to 7% of inspired O2 evoked typical hypoxia‐induced hyperventilation, which was not affected by vehicle and both doses of methysergide. However, WAY 100635 and SB 269970 injections caused an increased HVR, due to a higher tidal volume. The effect was more pronounced with the 5‐HT7 antagonist since both doses were capable of increasing the HVR. As to the 5‐HT1A antagonist, the increase of HVR was observed at the lower dose only. Therefore, the current data provide the evidence that 5‐HT acting on 5‐HT1A and 5‐HT7 receptors in the AVPO exert an inhibitory effect on the HVR.